how to fix the following error?

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Yasir Ali 2019-3-26

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https://ww2.mathworks.cn/matlabcentral/answers/452355-how-to-fix-the-following-error

评论： Jan 2019-4-4

采纳的回答： Yasir Ali

在 MATLAB Online 中打开

dear Seniors and Experts I need solution for following code kindly help me to fix it .

data is

y=195840*2 double 
fs=48000
t=0:0.001:2;                    % 2 secs @ 1kHz sample rate
      x=chirp(t,0,1,150);             % Start @ DC, cross 150Hz at t=1sec 
      F = 0:.1:100;
      [y,f,t,p] = spectrogram(x,256,250,F,1E3,'yaxis'); 
      % NOTE: This is the same as calling SPECTROGRAM with no outputs.
      surf(t,f,10*log10(abs(p)),'EdgeColor','none');   
      axis xy; axis tight; colormap(jet); view(0,90);
      xlabel('Time');
      ylabel('Frequency (Hz)');
[y,fs]=audioread('Mithe Mustafa Tey 5sec.mp3');
NW = round(fs*0.250);
[S,F,T,P] = spectrogram(y,NW,[],[],fs);

Error using spectrogram>chkinput (line 252)

X must be a vector (either row or column).

Error in spectrogram (line 166)

chkinput(x);

while I click on line 252 and 166 it shows this

line 252 = error(message('signal:spectrogram:MustBeVector', 'X'));

line 166 = chkinput(x);

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Answer 1

Yasir Ali 2019-3-26

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https://ww2.mathworks.cn/matlabcentral/answers/452355-how-to-fix-the-following-error#answer_367399

Thanks Dear walter If I wish to plot both channels then how to do that?

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Walter Roberson 2019-3-26

在 MATLAB Online 中打开

subplot(1,2,1)
spectrogram(y(:,1), NW, [], [], fs);
title('left channel')
subplot(1,2,2)
spectrogram(y(:,2), NW, [], [], fs);
title('right channel')

Jan 2019-4-4

@Yasir: This is not an answer, which solves the question. Marking it as "accepted" means, that your problem is solved by this answer. Please post comments in the section for comments.

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Answer 2

Walter Roberson 2019-3-26

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Your mp3 is stereo, 2 channels. spectrogram() can only process one channel at a time.

You need to do one of the following:

Choose one of the two channels and only process that one; or
combine the two channels into one, such as by using mean(); or
call spectrogram twice, once for each of the channels.

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Yasir Ali 2019-3-26

编辑：Walter Roberson 2019-3-30

Dear walter one last guideline require I found your comments very helpful

In above code I have try to get frequency response of audio in milisecond is it good code for getting frequency in miliseconds? ?

And when I try to get spectrum above 300 like 350 ms or more than error comes index dimension exceeds.

Walter Roberson 2019-3-30

I am not sure. My calculation at the moment is that with your window of 256 that you would get resolution to about 375 Hz, but I do not trust those calculations at all.

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